Cost-Basis Investment (Details Textual) (USD $)	1 Months Ended		0 Months Ended	1 Months Ended		3 Months Ended	6 Months Ended	12 Months Ended
	Apr. 20, 2011	Jun. 30, 2012	Apr. 29, 2013 Clearsign Combustion Corporation [Member]	Apr. 25, 2012 Clearsign Combustion Corporation [Member]	Apr. 20, 2011 Clearsign Combustion Corporation [Member]	Jun. 30, 2013 Clearsign Combustion Corporation [Member]	Jun. 30, 2013 Clearsign Combustion Corporation [Member]	Dec. 31, 2012 Clearsign Combustion Corporation [Member]	Apr. 24, 2012 Clearsign Combustion Corporation [Member]
Equity Method Investments Shares Acquired					363,636
Equity Method Investment, Aggregate Cost					$ 1,000,000
Equity Method Investments Per Share Value Of Shares Acquired					$ 2.75
Stock Issued During Period, Value, Private Offering Issues					3,000,000
Stockholders Equity Note, Stock Split, Conversion Ratio	1.25
Equity Method Investments Shares Acquired After Stock Split	454,545
Equity Method Investment, Ownership Percentage		20.00%
Sale of Stock, Number of Shares Issued in Transaction				3,000,000
Sale of Stock, Price Per Share				$ 4.00
Common Stock Dividend Declared									450,000
Common Stock Dividend Rate Percentage									$ 0.05513475
Shares Issuable For One Share Of Equity Method Investee									18.137
Common Stock Dividends, Shares							450,952
Common Stock Dividend Rounding Shares							952
Equity Method Investment, Realized Gain (Loss) on Disposal								811,713
Equity Method Investment Measured Cost Basis				1,803,808
Equity Method Investment Shares Retained After Dividend Distribution			3,593
Available-for-sale Securities, Gross Realized Gains						$ 24,475	$ 24,475